1. Field of the Invention
This invention relates to a method of interfacing a plurality of peripheral digital information gathering devices with a central digital computer.
2. Description of the Prior Art
The most relevant prior art known to the inventor consists of U.S. Pat. No. 3,631,403 to Asbo; U.S. Pat. No. 3,699,532 to Schaffer; U.S. Pat. No. 3,921,148 to Ophir; U.S. Pat. No. 4,058,680 to Curtis; and U.S. Pat. No. 4,082,922 to Chu.
The invention is believed to be properly classified in the following areas: U.S. Class 179, Subclass 7.1R; U.S. Class 364, Subclasses 200 and 900; and U.S. Class 370, Subclass 80.
Interfacing computers with peripherals such as cash registers presents many problems due to the range of speed, variety of signal types and levels, and complexity of signal structure. Indeed, the variety among different types of cash registers is enormous, and the only commercial computer controlled cash registers are those which incorporate a microprocessor directly into each cash register in addition to a central computer. The drawbacks of such a system are the excessive cost of all of the hardware and firmware required. Thus there is a problem in the prior art to provide an interfacing between a central computer and a variety of cash registers, plus possibly other peripherals, which is effective, simple and inexpensive, and operates on inexpensive transmission line.